The microelectronic device industry is highly competitive. To maintain a competitive edge, manufacturers must be able to quickly adapt their product lines to advancing technology and changing consumer demands. Many microelectronic products require a number of separate components, one or more of which must be dedicated to a particular product design. If a manufacturer orders an inventory of microelectronic components dedicated to one particular product, the inventory may have to be discarded or sold well below cost if sales of the product fall short of projected levels.
The memory module industry illustrates the difficulties inherent in predicting the market and minimizing manufacturing costs. Many computers and other processor-based systems employ either Single In-line Memory Modules (SIMMs) or Dual In-line Memory Modules (DIMMs). SIMMs and DIMMs each generally comprise a circuit board with a plurality of integrated circuit dies mounted thereon. The dies are often interchangeable and can be used on a wide variety of different SIMM or DIMM configurations. The circuit boards, however, are commonly specific to a particular SIMM or DIMM configuration. Manufacturer will order or produce an inventory of circuit boards for a particular SIMM or DIMM configuration. If market demands for that particular configuration fall short of projected demands, the manufacturer will be unable to use the inventory of specialized circuit boards for another memory module product. Oftentimes, if the manufacturer overestimates the demand for a particular memory module configuration, the demand for an alternative configuration will be underestimated. It can sometimes take weeks to redesign and stock an alternative configuration, leading to production delays and backlogs in customer orders.
U.S. Pat. No. 5,377,124 (Mohsen, the teachings of which are incorporated herein by reference) suggests a field programmable printed circuit board which employs a relatively complex, multi-layered circuit board and a specialized integrated circuit die, or “programmable interconnect chip,” mounted on the circuit board. The programmable interconnect chip includes circuitry which will route connections between the conductive traces provided on the rest of the circuit board. Ostensibly, by replacing one programmable interconnect chip with a different programmable interconnect chip, the circuit board can be adapted for different uses. Unfortunately, designing and producing such specialized integrated circuit dies can be a relatively expensive, time-consuming process. With some lower profit margin products, e.g., standard memory modules, the cost of such a specialized die may well outweigh the potential cost savings afforded by the adaptability of the basic circuit board.
Manufacturers of memory modules and other microelectronic device assemblies commonly test each module before it is shipped. If one of the integrated circuit dies mounted on the module is defective, the entire module may need to be discarded. In U.S. Pat. No. 5,953,216, the teachings of which are incorporated herein by reference, Farnworth et al. propose an apparatus and method for substituting a replacement device (e.g., a new integrated circuit die) for a defective component (e.g., a defective integrated circuit die). In accordance with this method, the defective component may be isolated by severing electrical connections between the component and the circuit board or the like to which the defective component is mounted. The replacement component may be attached to a replacement site on the circuit board and coupled to a dedicated replacement terminal on the circuit board, e.g., by wirebonding. Farnworth et al. employ a circuit board that includes a replacement site for all of the modules produced, including the majority of the modules that do not include any defective components. Leaving an empty replacement site in defect-free modules may be undesirable in some circumstances.